Single-Pole Grounding Fault Protection Method for DC Distribution Networks Based on Instantaneous Feature

Abstract

DC distribution networks employing a low-current grounding method offer high power supply reliability. However, when a single-pole grounding fault occurs on a feeder, the fault current characteristics are not distinct, making accurate fault identification and feeder protection challenging. Prolonged operation with the fault may cause insulation damage, potentially leading to pole–pole short-circuit faults and escalating the incident. Therefore, equipping the system with reliable and rapid feeder protection is crucial. This paper analyzes the fault current in a two-level VSC-based DC distribution system under single-pole grounding faults, clarifies the relationship between the transient current of the feeder and the line capacitive current, and further investigates the variation patterns of fault transient current and Teager-based signal-feature characteristics. Based on this, a single-pole grounding fault protection method utilizing the Teager instantaneous-current feature is proposed. The Teager energy operator is employed to extract the instantaneous current feature of each feeder, and a protection criterion is constructed using the dimensionless feature ratio between the faulty pole and the non-fault pole to identify the faulty feeder. A simulation model of the DC distribution network is built using MATLAB/Simulink. Simulation results show that the proposed protection method can adapt to various scenarios, including different line faults, fault locations, fault resistances, and noise, while demonstrating satisfactory performance.